A number of maladies afflict the spine, causing severe pain, loss of mobility and decreased quality of life. Some examples of such disorders include degenerative disc disease, scoliosis, spinal deformities and other spinal conditions. Additionally, vertebral fractures and other trauma can cause spinal suffering.
Some conditions can be treated by surgical techniques such as spinal fusion. In spinal fusion, vertebrae are fused together by bone growth to immobilize the vertebrae and reduce pain. In spinal fusion procedures, a small interbody device of plastic, titanium or other biocompatible material is inserted between the vertebrae in place of the natural intervertebral disc. Often a surgeon will perform an anterior procedure to insert the interbody device.
Once the interbody device is in place, a surgeon typically has two options for limiting the movement of the interbody device. According to the first technique, the interbody device is attached to the vertebrae from the back using bone screws. Unfortunately, this requires that the surgeon open the patient on both the anterior and posterior sides. According to the second technique, the surgeon installs a separate rigid plate that spans the vertebrae that need to be immobilized. One problem with this technique is that movement of the interbody device can assert impact forces on the plate causing the bone screws attaching the plate to the spine to back out.